In a trench gate-type semiconductor device, an on voltage in the semiconductor device can be reduced by arranging a plurality of trench gates so that a space between the adjacent trench gates becomes narrow. However, a semiconductor substrate is in contact with a surface electrode in a region between the trench gates, and when the space between the adjacent trench gates is narrow, a contact area between the semiconductor substrate and the surface electrode becomes small. Accordingly, a problem of increasing a contact resistance between the semiconductor substrate and the surface electrode and the like occur. Therefore, in Japanese Patent Application Publication No. 2006-324488 (Patent Literature 1), a space between bottom parts of the adjacent trench gates is narrow by widening only the bottom parts of the trench gates.